Evidence-based Medicine: Defining Evidence

The overall goals of evidence-based medicine (EBM)
are to provide physicians and medical
personnel with the best information available in the field so that the
clinical practices of these
professionals provide patients with the best possible care.

In the Western world, we are brought up
to think of science as a means of discovering the truth about the world we
live in.This truth consists
of facts and questions that have answers that are right or wrong (i.e.,
true or untrue) and, most often, only one answer is the right one.This idea of absolute truth leaves little or no room for
interpretation—something is one way or it isn’t—meaning that all
observations must be purely objective since anything that invites
interpretation cannot be certain, and therefore, must not be truth.While the concept of objective observation is key to the scientific
method, which is in turn the foundation for science as we know it today,
there are arguments that wholly objective observation may not even be
possible.Barry Brummett
argues, “The very nature of observation, the approach towards the
observed by the observer, is a linking of the two.Real detachment would mean no observation at all.Observation is participation...” (157).Brummet is saying that in order to observe, the observer enters a
situation, therefore altering the situation merely by being present.While this idea is very disturbing to many scientists since
it suggests that uncorrupted reality will then never be known to humans,
it is not a new concept for science: quantum mechanics has faced the same
problem since the conception of the study.As far as anyone knows at this time, it is impossible to study
quantum physics without interfering with the natural state of the
material.On a simpler conceptual level, when a wild animal senses that
it is being observed, its behavior changes to reflect the state of being
watched and in potential danger.

Medicine, being a child of the sciences,
valiantly struggles to adhere to this ideal of right or wrong answers
although all too often humanity gets in the way.The need to balance this idea with the realities of working with
actual people is very apparent throughout the text by Sackett et al.This conflict is illustrated right away in the introduction to the
text. One of the steps prescribed for practicing EBM is “critically
appraising that evidence for its validity (closeness to the truth)” (Sackett
et al. 4).Even within this
sentence we see the need for a single truth—“the truth”—even
while the search for that truth or the likeness to it is
subjective—“critically appraising,” a subjective process
based on personal judgment.

EBM’s next internal conflict comes in
the practicing of EBM: incorporating patient testimony into a clinical
analysis.Needless to say, a
patient’s personal testimony is highly subjective since the only means
of measurement and analysis are the patient’s own experiences thus far
(e.g., where in the body is the pain located? or how intense is the pain?
[Sackett et al. 26]).This
information is crucial to medical diagnosis since there is no other
readily available means of determining this information in a more
controlled, objective manner, and so despite the fact that this
information is highly subjective, it cannot be ignored.The EBM text that is being examined labels this information as
being “qualitative research” and implies that this information from
personal experience is inferior to “‘objective’ effects of
quantitative research” (Sackett et al. 21,
22).The text smoothly dismisses this issue as not being in their
area of expertise and yet states “we regard the integration of
qualitative research to be one of the major current challenges in EBM” (Sackett
et al. 21).Therefore, the
question becomes is this qualitative research/patient testimony evidence
or some other sort of information?The
EBM training text seems to suggest that it is something other than
evidence by their definition, since there is not a means of determining
this information’s “closeness to the truth.”

In practice, medical personnel often try
to compensate for this human subjectivity by recounting patients’
testimonies in medical jargon and in the passive voice, which often gives
the illusion of objectivity.This
tendency to objectify people and their subjective experiences is
illustrated in a study by Kathleen Welch of the University of
Missouri-Kansas City.This
study took traditional medical students and required them to take a
three-hour literature class that focused on literary connections to
medicine along with students from other disciplines.The medical students enrolled in this course had an overwhelming
tendency to focus on the disease or medical condition involved in the
story, which is not terribly surprising; however, these students also used
language that objectified the people in the story, ignoring the personal
experiences of the patients and any factors that were not related to
medical diagnosis or the specific plotline (Welch 313–317).These students are a good representation of the medical field’s
focus on the objective to the point of ignoring or altering the subjective
to fit preconceptions of what evidence should be.

This trend is found throughout the
medical field and the EBM text examined here and it has not gone unnoticed
by practitioners.An
editorial by Trisha Greenhalgh in the British Journal of Medicine
provides a good argument temporizing the sweeping claims and
generalizations that are often found in pro-evidence-based medicine texts.She highlights the issues of patients with a complex medical
history, which have many aspects and considerations, and the possible
treatment approaches: “Failure to recognize the legitimacy of these
variations in approach has created a somewhat spurious divide between
those who seek to establish general practice on an equal ‘scientific’
footing to that of the secondary care sector and those who emphasize the
value of the intuitive, narrative, and interpretive aspects of the
consultation” (Greenhalgh 958).This
still does not categorize this subjective information as evidence, but it
at least acknowledges the value of it.

Written by Amanda Fullan, University of
Wisconsin, Eau Claire
Last Updated December 15, 2001